LAMELLAR MORPHOLOGY BY SMALL-ANGLE X-RAY-SCATTERING MEASUREMENTS IN SOME PERFLUORINATED COPOLYMERS OF TETRAFLUOROETHYLENE

Some samples of tetrafluoroethylene copolymers, containing perfluoropr opyl vinyl ether, perfluoromethyl vinyl ether, and hexafluoropropene, were studied by small-angle X-ray scattering in order to investigate t he correlation among the crystalline lamellar thickness and both the c omonomer content and the molecular weight. The lamellar thickness was determined from the identity period of the one-dimensional scattering function and from the analysis of the one-dimensional correlation func tion. The crystallinity and the volume of the crystalline unit cell we re determined by wide-angle X-ray scattering. Some considerations are reported on the partial inclusion in the crystall cell of the -CF3 gro ups and on the expulsion into the amorphous regions of the -O(CF2)(2)C F3 groups.